1. Field of the Invention
The present invention relates to hearing aids. The invention further relates to a telephone adapted for communicating with a hearing aid. The invention also relates to a method of communicating with a hearing aid.
The invention more specifically relates to a telephone and to a programmable hearing aid to be located at or in the ear of a user. The invention more particularly relates to using such a hearing aid in co-operation with a telephone by creating a wireless link from the telephone to the hearing aid.
2. The Prior Art
WO-A1-2006/097099 describes a cell phone with a plug-in device for communicating with a hearing aid, whereby the cell phone with plug-in device can be used as a remote control for a hearing aid.
U.S. Pat. No. 7,657,049 B2 describes a telephone handset with a hearing aid compatible coil for inductively coupling with the telecoil at the hearing aid in order to inductively transmit sound from the telephone speaker to the telecoil of the hearing aid.
US-A1-20100128908 describes a telephone including a hearing aid chip for amplifying the acoustic output sound from the telephone according to the hearing threshold of the user.
Application PCT/DK2009/050274 filed on 15 Oct. 2009 in Denmark, and published as WO-A1-2011044898 describes a codec for coding and decoding of wirelessly transmitted data to and from a hearing aid to reduce the bit stream and hereby the power consumption of the hearing aid while maintaining a strong wireless signal for transferring data and sound to and from a hearing aid.
US-A1 2010/0142738 discloses a hearing aid where some settings can be controlled via acoustic signals. For instance if the hearing aid user whishes to increase the volume, he may do so by typing a prescribed key string on the telephone. This will give rise to a corresponding acoustic output from the telephone, which may be interpreted by the hearing aid as e.g. a volume control signal.
In the context of the present disclosure, a hearing aid is defined as a small, battery-powered device, comprising a microphone, an audio processor and an acoustic output transducer, configured to be worn in or behind the ear by a hearing-impaired person. By fitting the hearing aid according to a prescription calculated from a measurement of a hearing loss of the user, the hearing aid may amplify sound in certain frequency bands in order to compensate the hearing loss in those frequency bands. In order to provide an accurate and flexible amplification, most modern hearing aids are of the digital variety which can be programmed to fit the users prescription.
For many users of hearing aids today, the use of telephones in connection with their hearing aid is difficult, as relying on the acoustic path from the telephone speaker to the eardrum via the hearing aid does not provide the optimum rendering of the sound. This is especially a problem when using a “behind the ear” (BTE) hearing aid, as the microphones of such hearing aids are located above the ear, thereby removed from the telephone loudspeaker when the telephone is held in the normal position. Even a user skilled in positioning the telephone loudspeaker in a position closer to the microphone of the hearing aid, will experience a signal reduction of about 10-20 dB. At the contralateral ear, i.e. the ear opposite the one where the telephone is placed, there will be no signal at all.
Several manufacturers of hearing aids and telephone systems have tried to overcome this problem, in different ways. One common way to try to overcome this problem has been to rely on the coil of the telephone speaker to excite the telecoil of the hearing aid, whereby the sound from the telephone is transferred to the hearing aid inductively. However with many modern telephones, the speaker coil is too small to create a magnetic field with sufficient signal strength.
Another solution has been to Bluetooth-enable the hearing aid and then pair up the hearing aid with the telephone. A Bluetooth signal from the telephone can then be picked up by the hearing aid and decoded to form an amplified acoustic sound to the user of the hearing aid. This solution has several disadvantages. Bluetooth is very power consuming, the hearing aid and the telephone have to be paired, and because the Bluetooth link is very power consuming, the link has to be disabled after every call and then enabled and paired again before a new call, which is all very time consuming for answering a call. A further disadvantage when using Bluetooth technology is the delay time. When dealing with real time audio signals, the delay time should preferably be less than 10 ms. If the delay is more than approximately 10 ms the delay will be noticeable for the user, as the same sound arrives at the ear drum at a first time instance due to direct sound transmission and at a second time instance due to the sound being delayed by signal processing and transmission time. In Bluetooth devices the delay time is more than 10 ms.
Yet another solution has been to adjust the sound from the telephone to compensate the hearing impaired persons hearing loss. This has the disadvantage that the hearing impaired person would have to take off the hearing aids before making a phone call, and that the telephone would only be usable for the hearing impaired, as the sound would be much to loud for normal hearing people. Furthermore the telephone would have to be fitted by a hearing care professional to the exact hearing loss the impaired is suffering, something which would be very time consuming and costly.